Video monitoring systems are used in a variety of applications for monitoring objects within an environment. In security applications, for example, such systems are sometimes employed to track individuals or vehicles entering or leaving a building facility or security gate, or to monitor individuals within a store, office building, hospital, or other such setting where the health and/or safety of the occupants may be of concern. In the aviation industry, for example, such systems have been used to monitor the presence of individuals at key locations within an airport such as at a security gate or parking garage.
In certain applications, the video surveillance system may be tasked to record video image data for later use in determining the occurrence of a particular event. In forensic investigations, for example, it is common to task one or more video cameras within the system to indiscriminately record entire video clips that can later be analyzed to detect the occurrence of an event such as a robbery or theft. Such video images are typically stored as either analog video streams or as digital image data on a hard drive, optical drive, videocassette recorder (VCR), or other suitable storage means.
The process of indiscriminately storing video image data performed by many conventional surveillance systems has several drawbacks. First of all, such systems typically require a massive amount of storage space and processing capability, particularly in those instances where relatively large image sequences (e.g. a 24 hour surveillance tape) are acquired, or where the resolution and/or frame rate of the video cameras is set high. Moreover, the process of manually viewing such video images to detect the occurrence of an event within an image sequence can be time consuming and tedious, in some cases requiring the user to repeatedly scan through the image sequence until the desired event is found. While more modern surveillance systems provide a time and/or date stamp to facilitate recording and searching at specific periods of time, such systems lack the ability to record and index only those events of interest specified by the user.
In some applications, the video surveillance system will be used to assist an operator in performing a particular task. An operator such as a security guard, for example, will typically use such system by monitoring multiple screens of camera inputs while also performing other security-related duties. After some viewing time, user fatigue may limit the ability of the operator to effectively view the monitoring screens. Despite such user fatigue, many analog video surveillance systems do not provide any analysis on the monitor screens. In those video surveillance systems that do provide such analysis, only minimal analysis such as motion detection is typically provided, signaling to the operator that movement of an object within the FOV of a camera has occurred. While such systems are often adapted to present the raw video or motion-cued video to the operator when such motion detection, they do not prompt and/or alert the operator to the occurrence of a user-specified event.